. Operator (C# Reference)

 

Updated: July 20, 2015

For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

The dot operator (.) is used for member access. The dot operator specifies a member of a type or namespace. For example, the dot operator is used to access specific methods within the .NET Framework class libraries:

            // The class Console in namespace System:
            System.Console.WriteLine("hello");

For example, consider the following class:

        class Simple
        {
            public int a;
            public void b()
            {
            }
        }

            Simple s = new Simple();

The variable s has two members, a and b; to access them, use the dot operator:

            s.a = 6;   // assign to field a;
            s.b();     // invoke member function b;

The dot is also used to form qualified names, which are names that specify the namespace or interface, for example, to which they belong.

            // The class Console in namespace System:
            System.Console.WriteLine("hello");

The using directive makes some name qualification optional:

    
    namespace ExampleNS
    {
        using System;
        class C
        {
            void M()
            {
                System.Console.WriteLine("hello");
                Console.WriteLine("hello");   // Same as previous line.
            }
        }
    }

But when an identifier is ambiguous, it must be qualified:

    namespace Example2
    {
        class Console
        {
            public static void WriteLine(string s){}
        }
    }
    namespace Example1
    {
        using System;
        using Example2;
        class C
        {
            void M()
            {                
                // Console.WriteLine("hello");   // Compiler error. Ambiguous reference.
                System.Console.WriteLine("hello"); //OK
                Example2.Console.WriteLine("hello"); //OK
            }
        }
    }

For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.

C# Reference
C# Programming Guide
C# Operators

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